you should do the following b4 watch the avi files(99%):
1. go to the following page to download the codecs and intall them. http://superlightdns.twbbs.org/mpeg4/mpeg4_teach.php3
2. download xvid.exe and install it , you can find it on google.com
3. download the nimo codec pack and install it as the following article tells
you.